This invention relates to explosives detection by directional fast neutron beams scan with associated particles.
Existing means of inspection, such as X-ray screening and trace/vapor sensing are very deficient for detecting explosive substances. The former attempts to detect the explosives in the inspected items by looking at the shapes of the item. The latter attempts to collect traces or vapor from the outside of the inspected item. Both of these inspections techniques provide information that may or may not be related to the presence of explosives' inside the item.
Nuclear techniques, such as neutron-neutron, neutron-gamma and gamma-gamma, may detect explosives automatically through detection of its elemental constituents, primarily nitrogen and secondarily hydrogen. Due to the long penetration depth of neutrons (thermal and fast) and gamma ray, these nuclear techniques can provide the explosives elemental constituent's information deep inside the inspected items.
In neutron-based techniques, fast or thermal neutron induced (n, n gamma) reactions may provide information about the elemental composition in the depth of an inspected item. A fast neutron technique using “tagged neutrons” from a sealed neutron tube has recently been developed. This technique is promising. However, the usefulness of the technique is questionable because its sensitivity is low due to its use of a sealed neutron tube. As such, methods of detecting explosives in items are still needed that are more accurate and effective.